1. Field of the Invention
This invention relates to a cargo securing fitting adapted to be used for fixing a cargo on the floor of carriers such as cargo ships, vehicles, airplanes or the like. Particularly, the invention relates to such a cargo securing fitting comprising a base coupling member adapted to be secured or welded to the floor of the carrier and a removable cap coupling member connected to the base coupling member and having any one of a stacker cone, twist lock cone, padeye, eyering, cloverleaf cone and the like usable to fasten or lash a solid cargo, such as containers, plants, vehicles or the like on the floor of a carrier, thereby to prevent the cargo from shifting or otherwise collapsing during its transportation. In turn, the cap coupling member can be removed from the base coupling member to make the cargo space floor smooth and free for movement of a bulldozer or operation of a grab, when the load to be transported by the carrier is of bulk cargo, such as coals, ores, grains or other materials.
2. Prior Art
One of conventional cargo securing fittings is of a so-called slide-guide type including a base on which a U-shaped guide member is provided. This fitting has a disadvantage in that lashing means connected to the fitting is apt to slide in the guide member in a direction to be released from the opening of the guide member. Therefore, this known fitting can be merely used as a stacker cone against horizontal shifting force, but of no value to be a securing fitting against vertical force. Japanese patent Laid-Open Publication No. 37781/1976 discloses another cargo securing fitting. As shown in FIGS. 6 and 7 of the accompanying drawings, this fitting comprises a base connector member a having upwardly inwardly projecting flanges b around the edge of the base member, and a insert connector member c having downwardly outwardly projecting lugs d. Each of the flange and lug has an arcuate undercut to define a twisted and tapered engagement surface which corresponds to a portion of an imaginal truncated cone having an apex positioned at a point somewhat deviated from the common center of the base member and insert member.
The base connector member of this type has a relatively large space at the center area thereof. Firstly, its securing strength in vertical direction is insufficient due to relatively small engagement areas of the lugs of insert connector member with the flanges around the edge of the base connector member. Secondly, the flanges are apt to be damaged by bulldozer or grab during cargo operation due to the fact that the flanges of base member are inwardly protruded towards the large central space. Another disadvantage of the cargo securing fitting of this type resides in that difficult and costy machining operations are required to form the eccentrical twisted taper engagement surfaces on the flanges and lugs.